Elevation range adjustment issues.

[longrangehunter]

I ended up buying a Kahles 312II FFP scope w/the Mil 2 reticle and 0.01 mrad CCW turrets after reading more then a few articles and owning 2 other Kahles scopes.

I have it mounted in Talley medium tactical rings on their 20 MOA base, but I only have 8.5 Mils left in the turret adjustment range after zeroing it at 100 yards. Which seems odd for a 34 mm scope with 7.2'/100 yards of adjustment. The scope is 2.125" above the centerline of the bore, which shouldn't matter, although not much can be done w/tactical rings and base. So what's up? I can have a 30-40 MOA base made but I can't believe this scope would only have that much elevation adjustment left on my setup. Which is a Hart barreled Howa/Vanguard SA in 7mm-08.
8.5 Mils will get me out to almost 900 yards with a 200 yard zero, but I would prefer to have more and that the scope be more optically centered.

I've talked to two different people, Gary at Talley and Cameron at Murphy Precision. Both say the 2.125" height has nothing to do with the adjustment range, but Cameron thinks maybe something is up with the scope itself or the turret themselves but he knows nothing about these scopes. Which I don't see after shooting it yesterday, even after shooting a square and more vertical stings to make sure it was vertically centered over the bore. Cameron will make me a 30 or 40 MOA base out of thicker bar stock to cover the screws, but thinks I should ask around if anyone else has had this issue as well?

I have 8.5 mrad up left and 15.0 mrad below my 100 yd. zero in the scope, which is basically 1/3 in the upper end of the range, and I'd prefer to be more the the middle or slightly lower of that adjustment range.

Any thoughts?

 

[Desert Fox]

Something is off. Their 6-24 has 26.7 mil of elevation. The 3-12 probably is about the same. If your base has 20 MOA cant, you should have at least 20 mil available to you.

 

[longrangehunter]

Something is off. Their 6-24 has 26.7 mil of elevation. The 3-12 probably is about the same. If your base has 20 MOA cant, you should have at least 20 mil available to you.

I know, which is why I was so dumb founded. So I took a 2x4x8' screwed it to my 100m backer board, nailed a measuring tape to it, and taped off near the bottom 83" inches. The scope has a full 84" of travel at 100m. 235 0.01 clicks = 23.5 Mils = 84.6" +/-. Which left me looking at the base, so I took it off and measured the difference front .3600" rear .4900" = .1300", but the receiver has more then that based on my measurements, .1445" which were crude but I think I'm correct in thinking the 20 MOA base is cut wrong for the action, and/or my action is off slightly.

I did some math and .0014" would equal 1 MOA. If I measure center to center of my base location on the action at 4.75" and do the math: 4.75 x 2 x 3.1416 = 29.85; 29.85 / 360 = .083; .083 / 60 = .0014 which equals one MOA at 4.75 inches, 20 MOA would only need a .028" difference, which should bring the base difference f/r at .1730". If my measurements are right?

Anyway I spoke w/ Gary at Talley and he wasn't able to do the long math on paper or in his head for that matter, but basically sad to have someone remove material from the front or shim the back! Ya, so I'm having Cameron Murphy make me a new 30 MOA base.

 

[JohnB]

Longrangehunter

Had a set of Warne 700 bases. They also claim on the package to fit Vanguard actions. Measured the height of the bases. .254" rear, .144" front, for a difference of .110". Significantly different from the .1445" you measured on your action.

JohnB

 

[longrangehunter]

Hey John and Desert Fox,

Thanks for the info. I added the .0014" to your F/R difference and came up with .138" for a 20 MOA slope, .145" should be 25 MOA slope? (.0014" x 5 + .138" = .145") Well I had Cameron at Murphy Precision make me a 30 MOA base after talking it over with him. I mounted the base and shot the gun, I gained an additional 6.5 Mils at 100 m = 23.4" inches @ 100 m. Since it was a 30 MOA base vs. the 20 MOA base Talley had made, leaves a 13.4" difference between the two bases. 23.4"-10" (10 MOA)= 13.4". Which basically means the Talley base was probably cut wrong, and more like a 6.5 MOA slope since that's how the math worked out?

Cameron Murphy has made me two different bases and both have worked out very well. I would have never suspected that the base made by Talley could have been off, but after a lot of effort on my part and the help of a few others, like Ken at Kahles USA and Cameron Murphy I was able to get the full use out of my scope for the gun it's mounted on.

I now have 16.8 Mils of elevation out of 23.5 total. Which gets me out to 1330 yards and right at were the bullet goes subsonic. Which is perfect for the application intended.

Thanks Guys